Here is a nice site with pictures of NFS cars from all game versions.
If you played
Most Wanted, Underground 2, Pro Street, Underground, and created your own car, you can share it on NFSCars.net. Its all there.

List your car or see the others at nfs car showroom

photo credit: juanpol

photo credit: shanewarne_60000

On Fotoviva.co.uk there is a nice automotive category of car arts…
Click on the picture bellow to see it.